iio: light: tcs3472: Fix buffer alignment in iio_push_to_buffers_with_timestamp()

To make code more readable, use a structure to express the channel
layout and ensure the timestamp is 8 byte aligned.

Found during an audit of all calls of uses of
iio_push_to_buffers_with_timestamp().

Fixes tag is not strictly accurate as prior to that patch there was
potentially an unaligned write.  However, any backport past there will
need to be done manually.

Fixes: 0624bf84 ("iio:tcs3472: Use iio_push_to_buffers_with_timestamp()")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210501170121.512209-20-jic23@kernel.org

drivers/iio/light/tcs3472.c

@@ -64,7 +64,11 @@ struct tcs3472_data {
 	u8 control;
 	u8 atime;
 	u8 apers;
-	u16 buffer[8]; /* 4 16-bit channels + 64-bit timestamp */
+	/* Ensure timestamp is naturally aligned */
+	struct {
+		u16 chans[4];
+		s64 timestamp __aligned(8);
+	} scan;
 };
 
 static const struct iio_event_spec tcs3472_events[] = {
@@ -386,10 +390,10 @@ static irqreturn_t tcs3472_trigger_handler(int irq, void *p)
 		if (ret < 0)
 			goto done;
 
-		data->buffer[j++] = ret;
+		data->scan.chans[j++] = ret;
 	}
 
-	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
 		iio_get_time_ns(indio_dev));
 
 done: